1. Field of the Invention
The invention relates to an X-ray device, notably a device for X-ray fluoroscopy, which includes an X-ray source and an X-ray detector for the continuous formation of X-ray images of a patient from an invariable position of the X-ray source and the X-ray detector.
2. Description of the Related Art
X-ray devices of this kind are often used as an aid for monitoring surgical interventions performed on a patient. To this end, X-ray images of the examination zone of interest are continuously formed from a fixed position of the X-ray source and the X-ray detector; these images are displayed on-line on a monitor so that the attending physician can directly follow the intervention taking place. A problem is encountered, however, in that parts of the body of the physician, notably the hands, inadvertently and unobtrusively invade the zone between the patient and the X-ray source or the X-ray detector which is traversed by the invisible X-rays, so that the physician is also exposed to an X-ray dose. Despite the comparatively low dose incurred when invading the X-ray beam once, in the long term the hands of the physician could suffer in the case of frequent exposure.
U.S. Pat. No. 5,873,826 discloses a computed tomography device which includes a rotating X-ray source and a rotating X-ray detector and is provided with a light source which is arranged directly adjacent the X-ray source and also rotates. In order to prevent the hands of the attending physician from being exposed to an excessive X-ray dose, steps are taken such that the X-rays are switched off in a first angular range in which the hands of the physician normally work, the X-rays being switched on only in a second angular range (the remainder). In order to let the physician know the angular range in which the X-rays are switched off, this range is illuminated by means of the light source, the light source being switched off in the remaining angular range (or vice versa). Moreover, the deactivation of the X-ray source in the first angular range also ensures that the quality of the X-ray image is not degraded by the hands of the physician.
It is an object of the present invention to improve an X-ray device of the kind set forth by taking steps for the protection of the attendant staff.
This object is achieved by means of an X-ray device including an x-ray source and x-ray detector for continuous formation of X-ray images of a patient from an unvariable position of the X-ray source and the X-ray detector, and indicator means for illuminating and/or monitoring essentially the radiation zone over the patient which is transversed by X-rays.
In the CT device which is known from U.S. Pat. No. 5,873,826 only the zone between the X-ray source and the patient in a given angular range is visible to the physician and protected against X-rays; the zone between the X-ray detector and the patient, however, is not visible and not protected even when the X-ray detector is situated over the patient and the hand of the physician is working between the detector and the patient. In the X-ray device according to the invention, however, adjustment is made to the zone above the patient, irrespective of the position of the X-ray source and the X-ray detector, because the hands of the physician are normally present therein during an intervention. For example, in the case of a C-arm X-ray device the X-ray source occupies a position underneath the patient and the X-ray detector is situated over the patient, so that in such an X-ray device the indicator means are preferably provided on the X-ray detector so as to illuminate and monitor the radiation zone between the X-ray detector and the patient. In the X-ray device according to the invention the X-ray source is not switched off either in a given angular range or when the hand of the physician is in the radiation zone, because in that case image acquisition from a fixed position of X-ray source and the X-ray detector could not produce instantaneous X-ray images and hence monitoring of the intervention by the physician would be impossible. It is rather the responsibility of the physician himself or herself whether to invade the illuminated and/or monitored radiation zone with his or her hands; in the X-ray device in accordance with the invention, however, he or she is informed immediately when he or she does so.
Advantageous embodiments are disclosed notably in the further claims. The indicator means are preferably formed as optical indicator means for quasi-visualization of the zone traversed by the X-rays, as optical monitoring means for monitoring an intervention in the radiation zone and/or as acoustic alarm means for producing an acoustic alarm signal upon invasion of the radiation zone.